Process for the manufacture of octaalkylpyrophosphoramides



Patented Oct. 6, 1953 UN [TED STATES PROCESS FJOR THE MANUFACTURE OF"'OCTAAIJKYLPYROPHGSPHOTRNMIDES r-Tolkmith, i-Midland, Mic'h., assignortoZThc Dow ChemicaliCompanyfMidland,Mich,,a cor- No' Dmwing.ApfilicatiomAugustim,i951, .fSerial No. 2425404 IQQCIaIms.

ilrhe present invention is concerned with a.

phoramides .of'ithe formula inovel :process for the manufacture of,pyrophos- .iof hexaalkylphosphoramide t, PIn the above :and -succeedmgformula, i R i-repne- Isents fan ial-kyl radical crc'ontaining from lto"14 carbon a'toms, inclusive.

-The mew :process comprises sulij-ecting ta bisittetraalkyldiamidophosphoric) 'dialkylamidophosmhoric :dianhydride :of:the 'iormula to a temperature greater than 35 CL while iadmixed with--e 'hexaalkylphosphoramide of the .The .exact mechanics .zo'f thereaction "arenot completely understood. Some ioctaalkylpyrophosphoramideis produced 'under "the described reaction conditions regardless of the:proportions and "bisttetrafalkyldiamidophosphoric)'diallkylamidophosphoric dianhydride present in the reaction mixture.{In preferred practice, increased yields "6f the derated from the 2 Therate at which thejtormation of thepyrophosphoramides takes place hasbeen i found Ito vary directly with the temperature employed.

In the ,practice of the methodvof the invention.

the heating isigenerally carried out overa, period of from n-twoltotwelve .hours or longer, the longer periods of reaction being employedat the "lower temperatures.

In carrying out the process .of thevpreserit inventionfthe totalreactant charge maybe mechanically mixed and then heated .for a periodofitime. Lophosphoitic) dialkylamidophosphoric odi'arihydride "may "beadded portionwise to the hexa alkylphosphoramide under conditionsiofelevated temperature in the reaction vessel. Upon completion of "thereaction, low boiling constituents may "be 'strippedifrom the reactionmixture by distillation under reduced pressure, and Lpr'ferablyunder 190C.

The crude "reaction products as obtained in 'theipractice of'thepresentmethod may Lbeemthe octaalkylpyrophosp'horamide may be sepa- I reactionproduct by molecular distillation.

The bis(tetraalkyldiarnidophosphoric) dialkyl aniidophosphoric'dian'hydrides employed as "starting materials "in the .aforedescribed.process may *he produc'edby the method disclosed in my copen'dingapplication Serial No. 2423406 'filed "concurrently herewith. Theprocess comprises reacting together at a temperature .of "from to C. atleast-two molecular proportions of "a diamido compound of the formula HR\ l/P- X 5N FR/ and .one --molecular :-proportion of a. )monoamidocompound of thenformula an o :Y Nci R .whercin :is ;a :member of thegroup iconsisting bersotsaid group, and R is analkylnradicalaicontaining from 1 1304 carbon atoms, inclusive. llhe reactionninvolvesagcon'densation resulting in the formation of aalkyl chloride. inpractice, sub- Alternatively, the biSKtetraaIkyIdiamidstantially all thechlorine in the tetraalkyldiamidophosphoric chloride or thedialkylamidophosphoric dichloride may be recovered as alkyl chloride(RCl) In carrying out the reaction, the tetraalkyldiamido phosphoricchloride and the 0,0-dialkyl dialkylamidophosphate or the O-alkyltetraalkyldiamidophosphate and dialkylamidophosphoric dichloride remixed together and the resulting dispersion heated with stirring at atemperature of from 90 to 135 C. until no substantial amounts of alkylchloride of reaction are liberated. Upon completion of the reaction, themixture may be distilled under reduced pressure and under 135 C. toseparate low boiling constituents and to obtain as a residue the desiredbis(tetraalkyldiamidophosphoric) dialkylamidophosphoric dianhydride.

In carrying out the method of the present invention, it has been foundunnecessary to isolate the bis(tetraalkyldiamidophosphoric)dialkylamidophosphoric dianhydrides to be employed as startingmaterials. Thus, the new process may be carried out by subjecting eitherset of the precursors of the bis(tetraalkyldiamidophosphoric)dialkylamidophosphoric dianhydrides to a temperature greater than 135 C.while admixed with a suitable hexaalkylphosphoramide.

According to the latter procedure, a suitabletetraalkyldiamidophosphoric chloride and 0,0- dialkyldialkylamidophosphate are heated at a temperature greater than 135 C.while admixed with a suitable hexaalkylphosphoramide. Alternatively, theprocess may be carried out by subjecting a suitable O-alkyltetraalkyldiamidophosphate and dialkylamidophosphoric dichloride to atemperature greater than 135 C. while admixed with an appropriatehexaalkylphosphoramide. By-product alkyl chloride is formed when eitherset of the precursors of the bis(tetraalkyldiamidoohosphoric)dialkylamidophosphoric dianhydride is employed in the reaction mixture.In practice, substantially all of the chlorine in thetetraalkyldiamidophosphoric chloride or the dialkylamidophosphoricdichloride may be recovered as alkyl chloride.

In the practice of this further modification of the invention, at leastone molecular proportion of the hexaalkylphosphoramide is employed withan amount of the precursors of the bis(tetraalkyldiamidonhosphoric)dialkylamidophosphoric dianhydride to produce one molecular proportionof the latter phosphate compound. For example, at least one mole of thehexaalkylphosphoramide is employed with each 2 or more moles of thetetraalkyldiamidophosphoric chloride and one mole of the 0,0-dialkyldialkyldiamidophosphate, or with each 2 or more moles of the O-alkyltetraalkyldiamidophosphate and one mole of the dialkylamidophosphoricdichloride. As has been previously described, increased yields areobtained when a considerable excess of the hexaalkylphosphoramide isemployed.

When the precursors of the bis(tetraalkyldiamidophosphoric)dialkylamidophosphoric dianhydrides are employed in the reactionmixture, the formation of the octaalkylpyrophosphoramides has been foundto take place at a rate which varies directly with the employedtemperature. The heating is generally carried out over a period of fromtwo to twelve hours or longer, the longer reacting time being employedat the lower temperatures. The mixture may be heated under reducedpressure to facilitate the removal of alkyl chloride from the reactionzone. Follow ng the reaction, the desired product may be separated inthe previously described manner.

The following examples illustrate the invention but are not to beconstrued as limiting the same.

Example 1 7.85 grams (0.02 mole) ofbis(tetramethyldiamidophosphoric)dimethylamidophosphoric dianhydride,and 5.4 grams (0.03 mole) of hexamethylphosphoramide were mixed togetherand the resulting dispersion heated with agitation for five hours at 150C. Upon completion of the reaction, the mixture Was distilled underreduced pressure at gradually increased temperatures up to a temperatureof 170 C. to separate low boiling constituents and to contain as aresidue an octamethylpyrophosphoramide product having a molecular weightof 283 as compared to a theoretical molecular weight of 286.Octamethylpyrophosphoramide is an oily liquid having a boiling point of139 to 140 C. at 1.5 milliliters pressure and a refractive index n/D of1.4620 at 25 C.

Example 2 6.65 grams (0.04 mole) of O-methyl tetramethyldiamidophosphate(having a density of 1.0647 and a refractive index 'n/D of 1.4385 at 200.), 3.25 grams (0.02 mole) of dimethylamidophosphoric dichloride(having a density of 1.3502 and a refractive index n/D of 1.4640 at 20C.) and 5.4 grams (0.02 mole) of hexamethylphosphoramide were mixedtogether and the resulting dispersion heated at a. temperature of C.until the evolution of methyl chloride of reaction was substantiallycomplete. The heating was carried out with stirring and over a period ofabout five hours. During the heating, methyl chloride was separated andrecovered from the reaction zone as formed, Upon completion of thereaction, the mixture was distilled under reduced pressure at graduallyincreased temperatures up to a temperature of C. to separate low boilingconstituents and to obtain an octamethylpyrophosphoramide product as aresidue. When the latter product is fractionated in a molecular still,substantially pure octamethylpyrophosphoramide is obtained.

Example 3 6.8 (0.04 mole) of tetramethyldiamidophosphoric chloride(having a density of 1.1823 and a refractive index n/D of 1.4670 at 20C.), 3.65 grams (0.02 mole) of 0,0-diethyl dimethylamidophosphate(having a density of 1.1117 and a refractive index n/D of 1.4200 at 20C.) and 5.4 grams (0.03 mole) of hexamethylphosphoramide were mixedtogether and the resulting dispersion heated at a temperature of 150 C.until no further substantial amounts of ethyl chloride of reaction wereliberated. The heating was carried out with stirring and over a periodof about five hours. During the heating, gaseous ethyl chloride wasseparated and recovered from the reaction zone as formed. Uponcompletion of the reaction, the mixture was distilled under reducedpressure at gradually increased temperatures up to a temperature of 170C. to separate low boiling constituents and to obtain anoctamethylphosphoramide product as a residue. Upon fractionation in amolecular still, the latter product yields substantially pureoctamethylpyrophosphoramide.

In a similar manner other octaalkylpyrophosphoramides may be prepared asfollows:

Octaisopropylpyrophosphoramide by heating a mam 5 mixture of O-butyltetraisopropyldiamidophosphate, diisopropylamidophosphoric dichlorideand hexaisopropylphosphoramide.

Octaethylpyrophosphoramide by heating a mixture oftetraethyldiamidophosphoric chloride, 0,0-dibutyl diethylamidophosphateand hexaethylphosphoramide.

Octabutylpyrophosphoramide by heating a mixture oftetrabutyldiamidophosphoric chloride, 0,0-dimethy1 dibutylamidophosphateand hexabutylphosphoramide.

Octaethylpyrophosphoramide by heating a mixture of O-ethyltetraethyldiamidophosphate, diethylamidophosphoric dichloride andhexaethylphosphoramide. A i

I Octabutylpyrophosphoramide by heating a mixture ofbis(tetrabutyldiamidophosphoric) dibutylamidophosphoric dianhydride andhexabutylphosphoramide.

Octaethylpyrophosphoramide by heating a mixture ofbis(tetraethyldiamidophosphoric(diethylamidophosphoric dianhydride andhexaethylphosphoramide.

The octaalkylpyrophosphoramides as prepared in accordance with thepresent invention are oily liquids somewhat soluble in many organicsolvents and water. They are of value as intermediates for thepreparation of other phosphate derivatives and as toxic constituents ofparasiticide compositions. Their use for combatting insect pests isdisclosed in U. S. Patent No. 2,502,966.

I claim:

1. A process for the manufacture of a pyrophosphoramide of the formulawhich comprises subjecting a bis(tetraalkyldiamidophosphoric)dialkylamidophosphoric dianhydride of the formula,

to a temperature of from 135 to 190 C. while admixed with ahexaalkylphosphoramide of the formula R N )Ei R/ a which comprisessubjecting one molecular pro portion of a bis(tetraalkyldiamidophosphoric) dialkylamidophosphoric dianhydride of theformula the symbol R in the above formulae representing an alkyl radicalcontaining from 1 to 4 carbon atoms. inclusive.

' 3. A process for the manufacture of a pyrophosphoramide of the formulawhich comprises subjecting at least two molecular proportions of a.diamido compound of the formula R R /i x and one molecular proportion ofa monoamido compound of the formula to a temperature of from to C" whileadmixed with at least one molecular proportion of ahexaalkylphosphoramide of the formula in which formulae X is a member ofthe group consisting of chlorine and R'--O- and Y is the other member ofsaid group, and R and R each represent an alkyl radical containing from1 to 4 carbon atoms, inclusive.

4. A process for the manufacture of a pyrophosphoramide of the formulawhich comprises subjecting at least two molecuthe symbols Rand.in.the.a.bove formulaeeach representing an alkyllradical containinggfrom1 to 4 carbon atoms, inclusive. v

5. A process for the manufacture of a pyrophosphoramide of the formula?which comprises subjecting at least two molecular proportions of anO-alkyltetraalkyldiamidophosphate of the formula and one molecularproportion of a dialkylami'dophosphoric dichloride of the formula It.01. to-a"temperaturezofafrom435 to 190 C. while admixedv withh-at least;one: molecular proportion. of a hexaalkylphosphoramide of the formulathe symbols R and R" in theaboveformulae' each representing an alkylradical containing'froml to 4-carbonatoms, inclusive.

6; A process for the manufacture of'octamethylpyrophosphoramide whichcomprises subjecting at least two molecular proportions of O-methyltetramethyldiamidophosphate' oftheformula I -e '5 i -o-nm Q3: 1,

Cyr

and.onelmoleculariproportionoLdimethylamidm. phosphoric dichlorideoftheformula V cm o aor:

\ s re to a temperature of admixed with" at least one molecularproportion or"hexamethylphosphoramide 'ofthe formula '7. A process forthe manufacture of=octa=-- methylpyrophosphoramide which comprisessubjectingat leasttwmmolecularproportions oftetramethyldiamidophosphorica chloride of. the:

andsone. molecular; proportion of 0,0=-diethyl 'dl methylamidophosphateofithe formulav to a temperature or'from lac- C. while admixed with atleast one molecular proportion of hexamethylphosphoramide of the formula8. A processfor the manufacture of octamethylpyrophosphorami'derwhichcomprises sub-'- jectingone molecular proportion ofbis(tetramethyldiamidophosphoric) dimethylamidophosphoric dianhydride ofthe formula toaztemperatureo-f from 135 to 190 C. while admixed with atleast one molecular proportionof hexamethylphosphoramide of the formula9; A- prooess for'the manufacture or a pyrophosphoramide of the formulawhich comprises subjecting to atemperature of from 135 (70 190J'CI Whilefrom 135 to 190 of the formula C. a hexaalkylphosphoramide phoric)dialkylamidophosphoric dianhydride of the formula and (2) a mixture of adiamido compound of the formula and a monoamido compound of the formulaR/ \Y in the molecular proportion of at least 2 moles of the diamidocompound to 1 mole of the monoamido compound, X being a member of thegroup consisting of chlorine and R'-O-, Y being the other member of thelatter group and R and R each representing an alkyl radical containingfrom 1 to 4 carbon atoms, inclusive.

HENRY TOLKMITH.

N 0 references cited.

9. A PROCESS FOR THE MANUFACTURE OF A PYROPHOSPHORAMIDE OF THE FORMULA